class Solution {
public:
    int dx[4] = { 0, 0, 1, -1 };
    int dy[4] = { 1, -1, 0, 0 };
    int m, n;
    int numEnclaves(vector<vector<int>>& grid) {
        m = grid.size(), n = grid[0].size();
        vector<vector<bool>> vis(m, vector<bool>(n));
        queue<pair<int, int>> q;
        for (int i = 0; i < m; i++)
            for (int j = 0; j < n; j++)
            {
                if (i == 0 || i == m - 1 || j == 0 || j == n - 1)
                {
                    if (grid[i][j] == 1)
                    {
                        q.push({ i, j });
                        vis[i][j] = true;
                    }
                }
            }

        while (q.size())
        {
            int sz = q.size();
            while (sz--)
            {
                auto [a, b] = q.front();
                q.pop();
                for (int i = 0; i < 4; i++) {
                    int x = a + dx[i], y = b + dy[i];
                    if (x >= 0 && x < m && y >= 0 && y < n && grid[x][y] == 1 && !vis[x][y])
                    {
                        q.push({ x,y });
                        vis[x][y] = true;
                    }
                }
            }
        }

        int ret = 0;
        for (int i = 0; i < m; i++)
            for (int j = 0; j < n; j++)
            {
                if (grid[i][j] == 1 && !vis[i][j]) ret++;
            }
        return ret;
    }
};